1. Field of the Invention
This invention generally relates to power wrenches with reaction means adapted for wrenching closely spaced castellated nuts, such as are typically found on flanged connections.
2. Description of the Prior Art
Castellated nuts are used primarily for flanged connections requiring close inter-stud spacings. These nuts become subjected to very high torques during the wrenching operations. The studs used with castellated nuts frequently have an axial test hole adapted to receive a measuring rod for measuring the stretch of the stud which provides a corresponding measurement of the tension in the stud. Such measurements can alert to a possible failure of the flanged connection. A conventional wrench driver for torquing such castellated nuts comprises a wrench head having a plurality of equally-spaced radial lugs adapted for matingly engaging the radial slots of the castellated nuts. In use, due to the high driving torques exerted on the nuts through the slots, and on geometrical irregularities in the shapes of the slots and/or the lugs, the lugs when under torque tend to disengage from the slots by rising up on the walls of the slots. Any such disengagement between the driving lugs and their mating slots may cause serious damage to the walls of the slots and of the lugs. In addition, such disengagement considerably increases the total time required for turning and loosening the castellated nuts.